KR102409815B1 - Copper/ceramic bonded body, insulated circuit board, and copper/ceramic bonded body manufacturing method, and insulated circuit board manufacturing method - Google Patents

Abstract

A copper/ceramic bonded body formed by bonding a copper member 22 made of copper or a copper alloy and a ceramic member 11 made of aluminum nitride, between the copper member 22 and the ceramic member 11, in the matrix of Cu It is characterized in that the Mg solid solution layer 32 in which Mg is dissolved is formed.

Description

Copper/ceramic bonded body, insulated circuit board, and copper/ceramic bonded body manufacturing method, and insulated circuit board manufacturing method

The present invention relates to a copper/ceramic bonded body comprising a copper member made of copper or a copper alloy and a ceramic member made of aluminum nitride joined together, an insulated circuit board, and a method for manufacturing a copper/ceramic bonded body, and a method for manufacturing an insulated circuit board will be.

This application claims priority with respect to Japanese Patent Application No. 2018-159457 for which it applied to Japan on August 28, 2018, The content is used here.

In the power module, LED module, and thermoelectric module, a power semiconductor element, an LED element, and a thermoelectric element are joined to an insulated circuit board in which a circuit layer made of a conductive material is formed on one surface of the insulating layer.

For example, a power semiconductor element for large power control used to control wind power generation, electric vehicles, hybrid vehicles, etc. has a large amount of heat generated during operation, and therefore, as a substrate on which it is mounted, for example, BACKGROUND ART An insulated circuit board having a circuit layer formed by bonding a ceramic substrate made of aluminum nitride and a metal plate having excellent conductivity to one surface of the ceramic substrate has been widely used conventionally. As an insulated circuit board, the thing in which the metal layer was formed by bonding a metal plate to the other surface of a ceramic board|substrate is provided.

For example, Patent Document 1 proposes an insulated circuit board in which the first metal plate and the second metal plate constituting the circuit layer and the metal layer are copper plates, and the copper plate is directly bonded to the ceramic substrate by the DBC method. In this DBC method, the copper plate and the ceramic substrate are joined by generating a liquid phase at the interface between the copper plate and the ceramic substrate using the eutectic reaction of copper and copper oxide.

Moreover, in patent document 2, the insulated circuit board which formed the circuit layer and the metal layer by bonding a copper plate to one surface and the other surface of a ceramic substrate is proposed. In this insulated circuit board, a copper plate is disposed on one surface and the other surface of the ceramic substrate via an Ag-Cu-Ti-based brazing material, and the copper plate is joined by heat treatment (so-called active metal brazing). law). In this active metal brazing method, since the brazing material containing Ti, which is the active metal, is used, the wettability between the molten brazing material and the ceramic substrate is improved, and the ceramic substrate and the copper plate are favorably joined.

Moreover, the paste containing the powder which consists of a Cu-Mg-Ti alloy is proposed by patent document 3 as a bonding brazing material used when bonding a copper plate and a ceramic substrate in high temperature nitrogen gas atmosphere. In this patent document 3, it has a structure joined by heating at 560-800 degreeC in nitrogen gas atmosphere, Mg in a Cu-Mg-Ti alloy sublimes and does not remain|survive at a bonding interface, and titanium nitride (TiN) It is supposed that this is not formed substantially.

Japanese Laid-Open Patent Publication No. Hei 04-162756 Japanese Patent Publication No. 3211856 Japanese Patent Publication No. 4375730

However, as disclosed in Patent Literature 1, when bonding a ceramic substrate and a copper plate by the DBC method, the bonding temperature must be 1065° C. or higher (the eutectic point temperature of copper and copper oxide or higher). , there was a fear that the ceramic substrate deteriorated during bonding. Further, in the case of bonding in a nitrogen gas atmosphere or the like, there was a problem that atmospheric gas remained at the bonding interface and partial discharge was easily generated.

As disclosed in Patent Document 2, when a ceramic substrate and a copper plate are joined by an active metal brazing method, the brazing material contains Ag and Ag exists at the bonding interface, so migration is easy to occur and high It cannot be used for pressure-resistant applications. Moreover, since the bonding temperature was relatively high at 900°C, there was a fear that the ceramic substrate deteriorated. In addition, a titanium nitride phase and an intermetallic compound phase containing Ti were generated in the vicinity of the bonding surface of the ceramic substrate, and there was a fear that the ceramic substrate was cracked during high-temperature operation.

As disclosed in Patent Document 3, when a bonding brazing material made of a paste containing a powder made of a Cu-Mg-Ti alloy is used and bonding is performed in a nitrogen gas atmosphere, gas remains at the bonding interface, and the There was a problem that electric discharge was easy to occur. In addition, organic substances contained in the paste remained at the bonding interface, and there was a fear that bonding would become insufficient. In addition, an intermetallic compound phase containing Ti was generated in the vicinity of the bonding surface of the ceramic substrate, and there was a fear that the ceramic substrate was cracked during high-temperature operation.

The present invention has been made in view of the circumstances described above, and while a copper member and a ceramic member are reliably joined, it is excellent in migration resistance, and copper capable of suppressing the occurrence of cracks in ceramics during high-temperature operation / It aims to provide a ceramic bonded body, an insulated circuit board, and the manufacturing method of the above-mentioned copper/ceramics bonded body, and the manufacturing method of an insulated circuit board.

In order to solve the above problems and achieve the above object, the copper/ceramic bonded body of the present invention is a copper/ceramic bonded body comprising a copper member made of copper or a copper alloy and a ceramic member made of aluminum nitride joined together, It is characterized in that an Mg solid solution layer in which Mg is dissolved in a parent phase of Cu is formed between the copper member and the ceramic member.

In the copper/ceramic bonded body of this configuration, between the copper member made of copper or a copper alloy and the ceramic member made of aluminum nitride, an Mg solid solution layer in which Mg is dissolved in the matrix of Cu is formed, so that the ceramic member and the copper member Mg disposed therebetween is sufficiently diffused toward the copper member, and Cu and Mg are sufficiently reacted. Therefore, the interfacial reaction is sufficiently advanced at the bonding interface between the copper member and the ceramic member, and a copper/ceramic bonded body in which the copper member and the ceramic member are reliably joined can be obtained. In addition, since Ti, Zr, Nb, and Hf do not exist at the bonding interface between the Cu member and the ceramic member, the nitride phase of Ti, Zr, Nb, and Hf and the intermetallic compound phase containing Ti, Zr, Nb, and Hf It does not generate|occur|produce and it can suppress the crack of a ceramic member also at the time of high temperature operation.

Moreover, since Ag does not exist in the bonding interface of a Cu member and a ceramic member, it is excellent also in migration resistance.

In the copper/ceramic bonded body of the present invention, it is preferable that the area ratio of the intermetallic compound phase in the region from the bonding surface of the ceramic member toward the copper member to 50 µm is 15% or less.

In this case, since the area ratio of the intermetallic compound phase in the region from the bonding surface of the ceramic member to 50 µm toward the copper member side is 15% or less, in the vicinity of the bonding surface of the ceramic member, it is hard and brittle. Since there are not many intermetallic compound phases which are easy to carry out, it becomes possible to reliably suppress the crack of the ceramic member at the time of high temperature operation.

The insulated circuit board of the present invention is an insulated circuit board in which a copper plate made of copper or a copper alloy is bonded to the surface of a ceramic substrate made of aluminum nitride, and between the copper plate and the ceramic substrate, Mg is dissolved in a matrix of Cu. It is characterized in that a solid solution layer of Mg is formed.

In the insulated circuit board of this structure, while a copper plate and a ceramic board|substrate are reliably joined, it is excellent in migration resistance, and can use it reliably also on high withstand voltage conditions.

The occurrence of cracks in the ceramic substrate during high-temperature operation can be suppressed, and it can be used reliably even under high-temperature conditions.

In the insulated circuit board of this invention, it is preferable that the area ratio of the intermetallic compound phase in the area|region to 50 micrometers from the bonding surface of the said ceramic substrate toward the said copper plate side is 15 % or less.

In this case, since the area ratio of the intermetallic compound phase in the region from the bonding surface of the ceramic substrate to 50 µm toward the copper plate side is 15% or less, it becomes hard and brittle in the vicinity of the bonding surface of the ceramic substrate. There are not many easy intermetallic compound phases, and it becomes possible to suppress reliably the crack of a ceramic substrate at the time of high temperature operation.

The manufacturing method of the copper/ceramics bonded body of this invention is a manufacturing method of the copper/ceramics bonded body which manufactures the above-mentioned copper/ceramics bonded body, The Mg arrangement|positioning process of disposing Mg between the said copper member and the said ceramic member; A lamination process of laminating the copper member and the ceramic member via Mg, and a bonding process in which the copper member and the ceramic member laminated via Mg are pressed in the lamination direction and heat-treated in a vacuum atmosphere to bond is provided, and in the Mg batching step, the Mg amount is set within a range of 0.17 mg/cm 2 or more and 3.48 mg/cm 2 or less.

According to the method for manufacturing a copper/ceramic bonded body having this configuration, Mg is disposed between the copper member and the ceramic member, and heat treatment is performed in a vacuum atmosphere while pressing them in the lamination direction. There is no case where residues of

In the Mg batch process, since the amount of Mg is set within the range of 0.17 mg/cm 2 or more and 3.48 mg/cm 2 or less, a liquid phase necessary for the interfacial reaction can be sufficiently obtained. Accordingly, it is possible to obtain a copper/ceramic bonded body in which the copper member and the ceramic member are reliably joined.

Since Ti, Zr, Nb, and Hf are not used for bonding, a nitride phase of Ti, Zr, Nb, and Hf and an intermetallic compound phase containing Ti, Zr, Nb, and Hf exist in the vicinity of the bonding surface of the ceramic member. It is possible to obtain a copper/ceramic bonded body capable of suppressing cracking of the ceramic member during high-temperature operation.

Since Ag is not used for bonding, a copper/ceramic bonded body having excellent migration resistance can be obtained.

In the method for producing a copper/ceramic bonded body of the present invention, it is preferable that the pressure load in the bonding step is in the range of 0.049 MPa or more and 3.4 MPa or less, and the heating temperature is in the range of 500°C or more and 850°C or less. .

In this case, since the pressing load in the bonding step is within the range of 0.049 MPa or more and 3.4 MPa or less, the ceramic member, the copper member, and Mg can be brought into close contact, and the interfacial reaction thereof can be promoted during heating. .

Since the heating temperature in the said bonding process is 500 degreeC or more higher than the process temperature of Cu and Mg, in a bonding interface, a liquid phase can fully be generated. On the other hand, since the heating temperature in the said bonding process is 850 degrees C or less, it can suppress that a liquid phase produces|generates excessively. Moreover, the thermal load to a ceramic member becomes small, and deterioration of a ceramic member can be suppressed.

The manufacturing method of the insulated circuit board of this invention is a manufacturing method of the insulated circuit board which manufactures the above-mentioned insulated circuit board, The Mg arrangement|positioning process of arrange|positioning Mg between the said copper plate and the said ceramic substrate, The said copper plate and the said A lamination process of laminating a ceramic substrate through Mg, and a bonding process of bonding the copper plate laminated through Mg and the ceramic substrate by heat treatment in a vacuum atmosphere in a state in which the ceramic substrate is pressed in the lamination direction; In the Mg batch process, it is characterized by setting the amount of Mg within the range of 0.17 mg/cm 2 or more and 3.48 mg/cm 2 or less.

According to the manufacturing method of the insulated circuit board of this structure, since Mg is arrange|positioned between the said copper plate and the said ceramic board|substrate, and these are pressurized in the lamination direction, and heat-processed in a vacuum atmosphere, gas and organic matter remain at the bonding interface. There is no case where water, etc. remains.

In the Mg batch process, since the amount of Mg is set within the range of 0.17 mg/cm 2 or more and 3.48 mg/cm 2 or less, a liquid phase necessary for the interfacial reaction can be sufficiently obtained. Accordingly, it is possible to obtain an insulated circuit board in which the copper plate and the ceramic substrate are reliably joined. In addition, since Ti, Zr, Nb, and Hf are not used for bonding, in the vicinity of the bonding surface of the ceramic substrate, a nitride phase of Ti, Zr, Nb, or Hf and an intermetallic compound phase containing Ti, Zr, Nb, and Hf It does not exist, and the insulated circuit board which can suppress the crack of the ceramic board|substrate at the time of high temperature operation|movement can be obtained.

Since Ag is not used for bonding, an insulated circuit board excellent in migration resistance can be obtained.

In the manufacturing method of the insulated circuit board of this invention, it is preferable that the pressure load in the said bonding process becomes in the range of 0.049 MPa or more and 3.4 MPa or less, and it is within the range whose heating temperature is 500 degreeC or more and 850 degrees C or less.

In this case, since the pressing load in the bonding step is in the range of 0.049 MPa or more and 3.4 MPa or less, the ceramic substrate, the copper plate, and Mg can be brought into close contact, and the interfacial reaction thereof can be promoted during heating.

Since the heating temperature in the said bonding process is 500 degreeC or more higher than the process temperature of Cu and Mg, in a bonding interface, a liquid phase can fully be generated. On the other hand, since the heating temperature in the said bonding process is 850 degrees C or less, it can suppress that a liquid phase produces|generates excessively. Moreover, the thermal load to a ceramic substrate becomes small, and deterioration of a ceramic substrate can be suppressed.

According to the present invention, a copper/ceramic bonded body capable of reliably bonding a copper member and a ceramic member, excellent migration resistance, and suppressing the occurrence of ceramic cracks during high-temperature operation, an insulated circuit board, And it becomes possible to provide the manufacturing method of the above-mentioned copper/ceramics bonded body, and the manufacturing method of an insulated circuit board.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic explanatory drawing of the power module using the insulated circuit board (copper/ceramics bonded body) which is embodiment of this invention.
Fig. 2 is a schematic diagram of a bonding interface between a circuit layer (copper member) and a metal layer (copper member) and a ceramic substrate (ceramic member) of an insulated circuit board (copper/ceramic bonded body) according to an embodiment of the present invention.
3 is a flowchart showing a method for manufacturing an insulated circuit board (copper/ceramic bonded body) according to an embodiment of the present invention.
It is explanatory drawing which shows the manufacturing method of the insulated circuit board (copper/ceramics bonded body) which is embodiment of this invention.
5 is an observation result of a bonding interface between a copper plate and a ceramic substrate in a copper/ceramic bonded body of Example 1 of the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to attached drawing.

The copper/ceramic bonded body according to the present embodiment is constituted by bonding a ceramic substrate 11 as a ceramic member, a copper plate 22 (circuit layer 12) and a copper plate 23 (metal layer 13) as a copper member. It is made of an insulated circuit board (10).

In FIG. 1, the insulated circuit board 10 which is embodiment of this invention, and the power module 1 using this insulated circuit board 10 are shown.

The power module 1 includes an insulated circuit board 10 and a semiconductor element 3 joined to one side (upper side in FIG. 1 ) of the insulated circuit board 10 via a first solder layer 2 . ) and the heat sink 51 joined to the other side (lower side in FIG. 1) of the insulated circuit board 10 via the 2nd solder layer 8 is provided.

The insulated circuit board 10 includes a ceramic substrate 11, a circuit layer 12 disposed and formed on one surface (upper surface in FIG. 1) of the ceramic substrate 11, and the other of the ceramic substrate 11 The metal layer 13 arrange|positioned on the surface (lower surface in FIG. 1) is provided.

The ceramic substrate 11 prevents the electrical connection between the circuit layer 12 and the metal layer 13, and in this embodiment, it is comprised from aluminum nitride with high insulation. The thickness of the ceramic substrate 11 is set in the range of 0.2 mm or more and 1.5 mm or less, and 0.635 mm is preferable as for the thickness of the ceramic substrate 11 in this embodiment.

The circuit layer 12 is formed by bonding the copper plate 22 which consists of copper or a copper alloy to one surface of the ceramic substrate 11, as shown in FIG. In this embodiment, as the copper plate 22 which comprises the circuit layer 12, the rolled plate of oxygen-free copper is used. A circuit pattern is formed in this circuit layer 12, and the one surface (upper surface in FIG. 1) becomes the mounting surface on which the semiconductor element 3 is mounted. The thickness of the circuit layer 12 is set within the range of 0.1 mm or more and 1.0 mm or less, and in this embodiment, as for the thickness of the circuit layer 12, 0.6 mm is preferable.

The metal layer 13 is formed by bonding the copper plate 23 which consists of copper or a copper alloy to the other surface of the ceramic substrate 11, as shown in FIG. In this embodiment, as the copper plate 23 which comprises the metal layer 13, the rolled plate of oxygen-free copper is used. The thickness of the metal layer 13 is set in the range of 0.1 mm or more and 1.0 mm or less, and, in this embodiment, as for the thickness of the metal layer 13, 0.6 mm is preferable.

The heat sink 51 is for cooling the above-mentioned insulated circuit board 10, and in this embodiment, it becomes the heat sink comprised with the material with favorable thermal conductivity. In this embodiment, it is preferable that the heat sink 51 is comprised from copper or copper alloy excellent in thermal conductivity. The heat sink 51 and the metal layer 13 of the insulated circuit board 10 are joined through the 2nd soldering layer 8. As shown in FIG.

As shown in FIG. 4, the ceramic substrate 11 and the circuit layer 12 (copper plate 22), and the ceramic substrate 11 and the metal layer 13 (copper plate 23), the Mg film 25 It is interposed and joined.

In the bonding interface of the ceramic substrate 11 and the circuit layer 12 (copper plate 22) and the bonding interface of the ceramic substrate 11 and the metal layer 13 (copper plate 23), as shown in FIG. 2, Cu A Mg solid solution layer 32 in which Mg is dissolved is formed in the matrix.

The content of Mg in the Mg solid solution layer 32 is in the range of 0.01 atomic% or more and 3 atomic% or less. The thickness of the Mg solid solution layer 32 is in the range of 0.1 µm or more and 150 µm or less, and preferably, it is in the range of 0.1 µm or more and 80 µm or less.

The Mg solid solution layer 32 has a concentration gradient in which the Mg concentration gradually increases from the circuit layer 12 (metal layer 13) toward the ceramic substrate 11 side.

In this embodiment, from the bonding surface of the ceramic substrate 11 toward the copper plate 22 (circuit layer 12) and the copper plate 23 (metal layer 13) side, the intermetallic region in the area|region to 50 micrometers. It is preferable that the area ratio of a compound phase is 15 % or less.

As described above, if the area ratio of the intermetallic compound phase at the bonding interface is suppressed, the Cu-Mg intermetallic compound phase containing Cu and Mg may be dispersed in the Mg solid solution layer 32 . As a Cu _- Mg intermetallic compound phase, Cu2Mg, _CuMg2 , etc. are mentioned, for example.

Next, the manufacturing method of the insulated circuit board 10 which is this embodiment mentioned above is demonstrated with reference to FIG.3 and FIG.4.

(Mg batch process (S01))

As shown in FIG. 4, between the copper plate 22 used as the circuit layer 12, and the ceramic substrate 11, and between the copper plate 23 used as the metal layer 13, and the ceramic substrate 11, respectively, Mg is arrange|positioned do. In this embodiment, the Mg film 25 is formed by vapor-depositing Mg.

In this Mg arrangement step (S01), the amount of Mg to be placed is within the range of 0.17 mg/cm 2 or more and 3.48 mg/cm 2 or less.

(Lamination process (S02))

Next, the copper plate 22 and the ceramic substrate 11 are laminated via the Mg film 25 , and the ceramic substrate 11 and the copper plate 23 are laminated via the Mg film 25 . .

(Joining process (S03))

Next, the laminated copper plate 22, the ceramic substrate 11, and the copper plate 23 are pressed in the lamination direction, charged in a vacuum furnace and heated, and the copper plate 22, the ceramic substrate 11, and the copper plate (23) is joined.

It is preferable to carry out the pressing load in a bonding process (S03) into the range of 0.049 Mpa or more and 3.4 Mpa or less.

The heating temperature in the bonding step (S03) is preferably in the range of 500°C or more and 850°C or less.

The degree of vacuum in the bonding step (S03) is preferably within the range of 1×10 ^-6 Pa or more and 5×10 ^-2 Pa or less.

The holding time at the heating temperature is preferably in the range of 5 min or more and 180 min or less.

Although the temperature-fall rate at the time of temperature-falling from heating temperature (bonding temperature) to 480 degreeC is not specifically limited, 25 degreeC/min or less is preferable, and 20 degreeC/min or less is more preferable. Moreover, although the lower limit of the temperature-fall rate is not specifically limited, It is good also as 3 degreeC/min or more, and is good also as 5 degreeC/min or more.

As mentioned above, the insulated circuit board 10 which is this embodiment is manufactured by the Mg arrangement|positioning process (S01), the lamination|stacking process (S02), and the bonding process (S03).

(Heat sink bonding process (S04))

Next, a heat sink 51 is joined to the other surface side of the metal layer 13 of the insulated circuit board 10 . The insulated circuit board 10 and the heat sink 51 are laminated through a soldering material, charged in a heating furnace, and the insulated circuit board 10 and the heat sink 51 are interposed with the second solder layer 8 interposed therebetween. solder joint.

(Semiconductor element bonding process (S05))

Next, the semiconductor element 3 is joined to one surface of the circuit layer 12 of the insulated circuit board 10 by soldering.

The power module 1 shown in FIG. 1 is manufactured by the above process.

According to the insulated circuit board 10 (copper/ceramics bonded body) of this embodiment having the structure as described above, the copper plate 22 (circuit layer 12) and the copper plate 23 (metal layer 13) made of oxygen-free copper ) and a ceramic substrate 11 made of aluminum nitride are bonded via an Mg film 25, between the ceramic substrate 11 and the circuit layer 12 (copper plate 22), and the ceramic substrate 11 and Between the metal layer 13 (copper plate 23), since the Mg solid solution layer 32 in which Mg was dissolved in the matrix of Cu is formed, the ceramic substrate 11 and the copper plate 22 (circuit layer 12) And Mg disposed and formed between the copper plate 23 (metal layer 13) is sufficiently diffused toward the copper plate 22 (circuit layer 12) and the copper plate 23 (metal layer 13) side, and Cu and Mg is sufficiently reacted. Therefore, in the bonding interface, the interfacial reaction proceeds sufficiently, and the copper plate 22 (circuit layer 12), the copper plate 23 (metal layer 13), and the ceramic substrate 11 are reliably bonded to the insulated circuit board. (10) (copper/ceramic bonded body) can be obtained.

Since Ti, Zr, Nb, and Hf do not exist at the bonding interface between the copper plate 22 (circuit layer 12) and the copper plate 23 (metal layer 13) and the ceramic substrate 11, Ti, Zr, The nitride phase of Nb and Hf and the intermetallic compound phase containing Ti, Zr, Nb, and Hf are not produced|generated, and the crack of the ceramic substrate 11 can be suppressed also at the time of high temperature operation. The total content of Ti, Zr, Nb, and Hf at the bonding interface between the copper plate 22 (circuit layer 12) and the copper plate 23 (metal layer 13) and the ceramic substrate 11 is 0.3 mass% or less. It is preferable, and it is more preferable that it is 0.1 mass % or less.

Since Ag does not exist in the bonding interface of the ceramic substrate 11, the copper plate 22 (circuit layer 12), and the copper plate 23 (metal layer 13), it is excellent in migration resistance. The content of Ag at the bonding interface between the copper plate 22 (circuit layer 12) and the copper plate 23 (metal layer 13) and the ceramic substrate 11 is preferably 0.2 mass% or less, and 0.1 mass% or less. more preferably.

In this embodiment, from the bonding surface of the ceramic substrate 11 toward the copper plate 22 (circuit layer 12) and the copper plate 23 (metal layer 13) side, the intermetallic region in the area|region to 50 micrometers. When the area ratio of the compound phase is 15% or less, there are not many hard and brittle intermetallic compound phases in the vicinity of the bonding surface of the ceramic substrate 11, and cracking of the ceramic substrate 11 during high-temperature operation is reliably prevented. can be suppressed.

The area ratio of the intermetallic compound phase in the region from the bonding surface of the ceramic substrate 11 toward the copper plate 22 (circuit layer 12) and the copper plate 23 (metal layer 13) side to 50 µm is, It is preferable that it is 10 % or less, and it is more preferable that it is 8 % or less.

According to the manufacturing method of the insulated circuit board 10 (copper/ceramics bonded body) of this embodiment, the Mg arrangement|positioning process of arrange|positioning Mg (Mg film 25) between the copper plates 22 and 23 and the ceramic substrate 11. (S01), a lamination step (S02) of laminating the copper plates 22 and 23 and the ceramic substrate 11 via the Mg film 25, and the laminated copper plate 22, the ceramic substrate 11, the copper plate ( 23) is provided with the bonding step (S03) of bonding by heat treatment in a vacuum atmosphere under pressure in the lamination direction, so that no gas or organic residue remains at the bonding interface.

In the Mg batch step (S01), since the amount of Mg is set within the range of 0.17 mg/cm 2 or more and 3.48 mg/cm 2 or less, the liquid phase necessary for the interfacial reaction can be sufficiently obtained. Therefore, the insulated circuit board 10 (copper/ceramics joined body) in which the copper plates 22 and 23 and the ceramic board|substrate 11 were reliably joined can be obtained.

Since Ti, Zr, Nb, and Hf are not used for bonding, in the vicinity of the bonding surface of the ceramic substrate 11, a nitride phase of Ti, Zr, Nb, or Hf or an intermetallic compound containing Ti, Zr, Nb, or Hf The insulated circuit board 10 (copper/ceramics bonded body) which can suppress the crack of the ceramic board|substrate 11 at the time of a high temperature operation without a phase can be obtained.

Since Ag is not used for bonding, the insulated circuit board 10 (copper/ceramic bonded body) excellent in migration resistance can be obtained.

When the amount of Mg is less than 0.17 mg/cm 2 , the amount of the liquid phase generated is insufficient, and there is a fear that the bonding rate is lowered. Moreover, when the amount of Mg exceeds 3.48 mg/cm 2 , the amount of the generated liquid phase becomes excessive, the liquid phase leaks from the bonding interface, and there is a fear that a bonded body having a predetermined shape cannot be manufactured. Moreover, the Cu-Mg intermetallic compound phase was produced|generated excessively, and there existed a possibility that a crack may arise in the ceramic substrate 11. As shown in FIG.

From the above, in this embodiment, the amount of Mg is made into the range of 0.17 mg/cm<2> or more and 3.48 mg/cm<2> or less.

The lower limit of the amount of Mg is preferably 0.24 mg/cm 2 or more, more preferably 0.32 mg/cm 2 or more. On the other hand, the upper limit of the amount of Mg is preferably 2.38 mg/cm 2 or less, and more preferably 1.58 mg/cm 2 or less.

In the present embodiment, since the pressing load in the bonding step S03 is 0.049 MPa or more, the ceramic substrate 11, the copper plates 22 and 23, and the Mg film 25 can be brought into close contact with each other and heated. It is possible to promote their interfacial reaction at the time. Since the pressing load in the bonding step S03 is 3.4 MPa or less, cracking of the ceramic substrate 11 in the bonding step S03, etc. can be suppressed.

It is preferable to set it as 0.098 MPa or more, and, as for the lower limit of the pressure load in a bonding process (S03), it is more preferable to set it as 0.294 MPa or more. On the other hand, it is preferable to set it as 1.96 MPa or less, and, as for the upper limit of the pressure load in a bonding process (S03), it is more preferable to set it as 0.98 MPa or less.

In the present embodiment, since the heating temperature in the bonding step (S03) is set to 500° C. or higher, which is higher than the processing temperature of Cu and Mg, a liquid phase can be sufficiently generated at the bonding interface. On the other hand, since the heating temperature in the bonding process (S03) is 850 degrees C or less, it can suppress that a liquid phase produces|generates excessively. Moreover, the thermal load with respect to the ceramic substrate 11 becomes small, and deterioration of the ceramic substrate 11 can be suppressed.

The lower limit of the heating temperature in the bonding step (S03) is preferably 600°C or higher, more preferably 680°C or higher. On the other hand, it is preferable to set it as 800 degrees C or less, and, as for the upper limit of the heating temperature in bonding process (S03), it is more preferable to set it as 760 degrees C or less.

In the present embodiment, when the degree of vacuum in the bonding step (S03) is within the range of 1 × 10 ^-6 Pa or more and 5 × 10 ^-2 Pa or less, oxidation of the Mg film 25 can be suppressed, It becomes possible to join the ceramic substrate 11 and the copper plates 22 and 23 reliably.

The lower limit of the vacuum degree in the bonding step (S03) is preferably 1×10 ⁻⁴ Pa or more, more preferably 1×10 ⁻³ Pa or more. On the other hand, the upper limit of the degree of vacuum in the bonding step (S03) is preferably 1 × 10 ^-2 Pa or less, more preferably 5 × 10 ^-3 Pa or less.

In this embodiment, when the holding time at the heating temperature in the bonding step (S03) is within the range of 5 min or more and 180 min or less, a liquid phase can be sufficiently formed, and the ceramic substrate 11 and the copper plate ( 22, 23) can be reliably joined.

The lower limit of the holding time at the heating temperature in the bonding step (S03) is preferably 10 min or more, more preferably 30 min or more. On the other hand, the upper limit of the holding time at the heating temperature in the bonding step (S03) is preferably 150 min or less, more preferably 120 min or less.

As mentioned above, although embodiment of this invention was described, this invention is not limited to this, It can change suitably in the range which does not deviate from the technical idea of the invention.

For example, although the copper plate which comprises a circuit layer or a metal layer was demonstrated as a rolled plate of oxygen-free copper, it is not limited to this, The thing comprised with other copper or copper alloy may be sufficient.

In this embodiment, the circuit layer and the metal layer have been described as being composed of a copper plate, but it is not limited to this, and if at least one of the circuit layer and the metal layer is composed of a copper plate, the other is composed of another metal plate such as an aluminum plate. okay

In the present embodiment, in the Mg arrangement step, the Mg film is formed by vapor deposition. However, the present embodiment is not limited thereto, and the Mg film may be formed by another method or an Mg foil may be disposed. Moreover, you may arrange|position a clad material of Cu and Mg.

In the present embodiment, in the Mg arrangement step, Mg paste and Cu-Mg paste may be applied. Moreover, you may laminate|stack and arrange|position Cu paste and Mg paste. In this case, the Mg paste may be disposed on either the copper plate side or the ceramic substrate side. Moreover, as Mg _, you may arrange|position MgH2.

Although a heat sink was mentioned as an example and demonstrated as a heat sink, it is not limited to this, There is no limitation in particular in the structure of a heat sink. For example, the heat sink may have a flow path through which the refrigerant flows, or may be provided with a cooling fin. Moreover, as a heat sink, the composite material (For example, AlSiC etc.) containing aluminum or an aluminum alloy can also be used.

Between the top plate part of a heat sink, a heat sink, and a metal layer, you may provide the buffer layer which consists of aluminum, an aluminum alloy, or the composite material containing aluminum (for example, AlSiC etc.).

In this embodiment, although the power semiconductor element is mounted on the circuit layer of the insulated circuit board and the power module is comprised, it is not limited to this. For example, an LED element may be mounted on an insulated circuit board, and a LED module may be comprised, and a thermoelectric module may be comprised by mounting a thermoelectric element in the circuit layer of an insulated circuit board.

Example

(Invention Examples 1 to 12, Comparative Examples 1 to 2, Conventional Examples)

A confirmation experiment performed to confirm the effectiveness of the present invention will be described.

A copper plate (oxygen-free copper, 37 mm long, 0.15 mm thick) having Mg disposed thereon as shown in Table 1 was laminated on both sides of a ceramic substrate made of aluminum nitride having a width of 40 mm, and under the bonding conditions shown in Table 1, By bonding, a copper/ceramic bonded body was formed. The thickness of the ceramic substrate was set to 0.635 mm in thickness. In addition, the vacuum degree of the vacuum furnace at the time of bonding was made into 5x10 ^-3 Pa.

In the conventional example, an active brazing material of Ag-28 mass% Cu-5 mass% Ti was disposed between the ceramic substrate and the copper plate so that the Ag amount was 5.2 mg/cm 2 .

In addition, in the bonding step (S03), when the temperature was decreased from the bonding temperature (“temperature (°C)” in Table 1) to 480°C, the temperature-fall rate was controlled so that the temperature was decreased at a rate of 5°C/min. In addition, the temperature-fall rate is controlled by the gas partial pressure (the presence or absence of circulation by a cooling fan) at the time of gas cooling.

For the thus-obtained copper/ceramics bonded body, the bonding interface was observed to confirm the Mg solid solution layer and the Cu-Mg intermetallic compound phase. Further, the initial bonding rate of the copper/ceramic bonded body, cracking and migration properties of the ceramic substrate after the cooling/heating cycle were evaluated as follows.

(Mg employment class)

The bonding interface between the copper plate and the ceramic substrate was observed using an EPMA apparatus (JXA-8539F manufactured by Nippon Electronics Co., Ltd.) under the conditions of a magnification of 2000 times and an acceleration voltage of 15 kV, and a region (400 µm × 600 µm) including the bonding interface was observed. Then, quantitative analysis was performed in a range of 10 or more and 20 or less depending on the thickness of the copper plate at 10 μm intervals from the surface of the ceramic substrate toward the copper plate side, and the region in which the Mg concentration was 0.01 atomic% or more was used as the Mg solid solution layer.

(area ratio of Cu-Mg intermetallic compound phase)

The bonding interface between the copper plate and the ceramic substrate was set using an electron beam microanalyzer (JXA-8539F manufactured by Nippon Electronics Co., Ltd.) in a region including the bonding interface at a magnification of 2000 times and an acceleration voltage of 15 kV (400 µm × 600 µm) Elemental MAP of Mg was obtained, and Cu concentration satisfies 5 atomic% or more and Mg concentration satisfies 30 atomic% or more and 70 atomic% or less as a 5-point average of quantitative analysis within a region where the presence of Mg was confirmed. The region was made of Cu-Mg intermetallic phase.

And the area ratio (%) of the intermetallic compound phase in the area|region to 50 micrometers toward the copper plate side from the bonding surface of a ceramic substrate was computed.

(Initial bonding rate)

The bonding rate of a copper plate and a ceramic board|substrate was calculated|required using the following formula using the ultrasonic flaw detection apparatus (Hitachi Power Solutions Co., Ltd. product FineSAT200). The initial bonding area was defined as the area to be bonded before bonding, ie, the area of the bonding surface of the copper plate. In the ultrasonic flaw detection image, since peeling is represented by a white part in a junction part, the area of this white part was made into the peeling area.

(Initial bonding rate) = {(Initial bonding area) - (Peeling area)}/(Initial bonding area)

(Crack of ceramic substrate)

Using a cold-heat shock tester (TSA-72ES manufactured by SPEC Co., Ltd.), 300 cycles of -50°C × 10 minutes ←→ 150°C × 10 minutes were performed in the gas phase.

The presence or absence of the crack of the ceramic board|substrate after loading the above-mentioned cooling/heating cycle was evaluated.

(migration)

In the circuit layer, the electrical resistance between the circuit patterns was measured after 2000 hours of standing under the conditions of a distance of 0.5 mm, a temperature of 85° C., a humidity of 85% RH, and a voltage of DC 50 V, and the resistance value was 1 × When it became 10 ⁶ Ω or less, it was judged that a short circuit (migration occurred) was judged, and evaluation of migration was made into "B". Under the same conditions as above, after standing for 2000 hours, the electrical resistance between the circuit patterns is measured, and when the resistance value is greater than 1 × 10 ⁶ Ω, it is judged that migration has not occurred, and the evaluation of migration is “A”. did

Table 1 shows the evaluation results. Moreover, the observation result of this invention Example 1 is shown in FIG.

In the Mg arrangement step, in Comparative Example 1 with an Mg content of 0.09 mg/cm 2 , less than the range of the present invention, since the liquid phase was insufficient during bonding, a bonded body could not be formed. For this reason, subsequent evaluation was stopped.

In the Mg batch process, in Comparative Example 2, where the Mg amount was 4.75 mg/cm 2 , which was higher than the range of the present invention, since the liquid phase was excessively generated during bonding, the liquid phase leaked from the bonding interface to produce a bonded body having a predetermined shape. couldn't For this reason, subsequent evaluation was stopped.

In the conventional example in which the ceramic substrate and the copper plate were joined using the Ag-Cu-Ti brazing material, evaluation of migration was judged as "B". It is presumed that this is because Ag was present at the bonding interface.

In contrast, in Examples 1 to 12 of the present invention, the initial bonding rate was also high, and cracking of the ceramic substrate was not observed. Moreover, migration was also favorable.

Moreover, as shown in FIG. 5, when the bonding interface was observed, the Mg solid solution layer 32 was observed.

(Inventive Examples 21 to 32)

The copper/ceramic bonded body was prepared in the same manner as the copper/ceramic bonded body prepared in Inventive Examples 1 to 12, and the area ratio of Cu ₂ Mg and the ultrasonic bonding interface were determined as follows for the obtained copper/ceramic bonded body. evaluated.

The Mg solid solution layer, the area ratio of the Cu-Mg intermetallic compound phase, and the initial bonding rate of the copper/ceramic bonded body were evaluated in the same manner as in the evaluations performed in Examples 1 to 12 of the present invention above.

(Temperature fall rate)

In the bonding step (S03), when the temperature was decreased from the bonding temperature (“temperature (°C)” in Table 2) to 480°C, the temperature-fall rate was controlled at the rate shown in Table 2.

(area ratio of Cu ₂ Mg)

Among the said Cu _- Mg intermetallic compound phases, the area ratio (%) of Cu2Mg was defined and calculated by the following formula.

Area ratio of Cu ₂ Mg (%) = area of Cu ₂ Mg/(area of Cu ₂ Mg + area of CuMg ₂ ) x 100

The “area of Cu ₂ Mg” was defined as a region in which the Mg concentration was 30 at% or more and less than 60 at%, and the “area of CuMg ₂ ” was defined as a region in which the Mg concentration was 60 at% or more and less than 70 at%.

(ultrasonic bonding)

With respect to the obtained copper/ceramics bonded body, using an ultrasonic metal bonding machine (manufactured by Choonpa Industrial Co., Ltd.: 60C-904), a copper terminal (10 mm × 5 mm × 1.5 mm thick) was ultrasonically bonded under the condition of a collapsing amount of 0.5 mm. did.

After bonding, using an ultrasonic flaw detector (FineSAT200, manufactured by Hitachi Power Solutions, Inc.), the bonding interface between the copper plate and the ceramic substrate was inspected. Also not confirmed was evaluated as "A". Table 2 shows the evaluation results.

The value of the area ratio of Cu ₂ Mg and the bonding property of ultrasonic bonding changed depending on the temperature-fall rate after the bonding step (S03).

From the result shown in Table 2, it became clear that 25 degreeC/min or less is preferable and, as for the temperature-fall rate, 20 degreeC/min or less is more preferable.

From the result shown in Table 2, it became clear that 55 % or more is preferable, 60 % or more is more preferable, and, as for the area ratio of Cu ₂ Mg among the Cu-Mg intermetallic compound phases, 67 % or more is still more preferable.

From the above, according to the example of the present invention, a copper/ceramic bonded body (insulation) capable of reliably bonding a copper member and a ceramic member, having excellent migration resistance, and suppressing the occurrence of ceramic cracks during high-temperature operation It was confirmed that it was possible to provide a circuit board).

Further, according to the example of the present invention, by controlling the rate of the temperature drop from the bonding temperature to 480°C, a copper/ceramic bonded body (insulated circuit board) that is reliably bonded to a copper member and a ceramic member and has excellent ultrasonic bonding properties can be provided it was confirmed

According to the present invention, a copper/ceramic bonded body capable of reliably bonding a copper member and a ceramic member, excellent migration resistance, and suppressing the occurrence of ceramic cracks during high-temperature operation, an insulated circuit board, And it becomes possible to provide the manufacturing method of the above-mentioned copper/ceramics bonded body, and the manufacturing method of an insulated circuit board.

10: insulated circuit board
11: ceramic substrate
12: circuit layer
13: metal layer
22, 23: copper plate
32: Mg employment layer

Claims (8)

A copper/ceramic bonded body comprising a copper member made of copper or a copper alloy and a ceramic member made of aluminum nitride joined together,
A copper/ceramics bonded body according to claim 1, wherein a Mg solid solution layer in which Mg is dissolved in a matrix of Cu is formed between the copper member and the ceramic member. The method of claim 1,
A copper/ceramic bonded body according to claim 1, wherein the area ratio of the intermetallic compound phase in a region from the bonding surface of the ceramic member toward the copper member side to 50 µm is 15% or less. An insulated circuit board in which a copper plate made of copper or a copper alloy is bonded to a surface of a ceramic substrate made of aluminum nitride, the insulated circuit board comprising:
An insulated circuit board characterized in that a Mg solid solution layer in which Mg is dissolved in a matrix of Cu is formed between the copper plate and the ceramic substrate. 4. The method of claim 3,
The area ratio of the intermetallic compound phase in the area|region from the bonding surface of the said ceramic substrate toward the said copper plate side to 50 micrometers is 15 % or less, The insulated circuit board characterized by the above-mentioned. A method for producing a copper/ceramic bonded body comprising the copper/ceramic bonded body according to claim 1 or 2, comprising:
an Mg arrangement step of disposing Mg between the copper member and the ceramic member;
a lamination step of laminating the copper member and the ceramic member via Mg;
a bonding step of bonding the copper member laminated via Mg and the ceramic member in a state in which the ceramic member is pressed in a lamination direction, and heat-treated in a vacuum atmosphere;
In the Mg batch step, the Mg amount is set to be within a range of 0.17 mg/cm 2 or more and 3.48 mg/cm 2 or less. 6. The method of claim 5,
A method for producing a copper/ceramic bonded body, wherein the pressure load in the bonding step is in the range of 0.049 MPa or more and 3.4 MPa or less, and the heating temperature is in the range of 500°C or more and 850°C or less. As a manufacturing method of the insulated circuit board of Claim 3 or 4,
an Mg arrangement step of disposing Mg between the copper plate and the ceramic substrate;
a lamination process of laminating the copper plate and the ceramic substrate via Mg;
A bonding step of bonding the copper plate laminated through Mg and the ceramic substrate by heat treatment in a vacuum atmosphere in a state in which the ceramic substrate is pressed in the lamination direction;
In the Mg arrangement step, the Mg amount is set to be within the range of 0.17 mg/cm 2 or more and 3.48 mg/cm 2 or less. 8. The method of claim 7,
The pressure load in the said bonding process is in the range of 0.049 MPa or more and 3.4 MPa or less, and the heating temperature is in the range of 500 degreeC or more and 850 degrees C or less, The manufacturing method of the insulated circuit board characterized by the above-mentioned.

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